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112 lines
3.4 KiB
C++
112 lines
3.4 KiB
C++
// Part of the Concrete Compiler Project, under the BSD3 License with Zama
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// Exceptions. See
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// https://github.com/zama-ai/concrete-compiler-internal/blob/main/LICENSE.txt
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// for license information.
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#include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
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#include "mlir/Dialect/Func/IR/FuncOps.h"
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#include "mlir/Transforms/DialectConversion.h"
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#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
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#include "concretelang/Dialect/FHE/IR/FHEOps.h"
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#include "concretelang/Dialect/FHE/Transforms/Max/Max.h"
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namespace arith = mlir::arith;
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namespace func = mlir::func;
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namespace FHE = mlir::concretelang::FHE;
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/// This rewrite pattern transforms all instances
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/// of `FHE.max_eint` to `max(x - y, 0) + y`.
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struct MaxEintPattern : public mlir::OpRewritePattern<FHE::MaxEintOp> {
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MaxEintPattern(mlir::MLIRContext *context)
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: mlir::OpRewritePattern<FHE::MaxEintOp>(context) {}
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mlir::LogicalResult
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matchAndRewrite(FHE::MaxEintOp maxEintOp,
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mlir::PatternRewriter &rewriter) const override {
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const mlir::Location loc = maxEintOp->getLoc();
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const FHE::FheIntegerInterface outputTy =
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maxEintOp->getResult(0).getType().cast<FHE::FheIntegerInterface>();
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const int64_t outputBitWidth = outputTy.getWidth();
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mlir::Value x = maxEintOp.x();
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mlir::Value y = maxEintOp.y();
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const auto xTy = x.getType().cast<FHE::FheIntegerInterface>();
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const auto yTy = y.getType().cast<FHE::FheIntegerInterface>();
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const auto signedTy = FHE::EncryptedSignedIntegerType::get(
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this->getContext(), outputBitWidth);
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if (xTy.isUnsigned()) {
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x = rewriter.create<FHE::ToSignedOp>(loc, signedTy, x).getResult();
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}
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if (yTy.isUnsigned()) {
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y = rewriter.create<FHE::ToSignedOp>(loc, signedTy, y).getResult();
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}
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const mlir::Value sub =
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rewriter.create<FHE::SubEintOp>(loc, x, y).getResult();
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const int64_t lutSize = 1 << outputBitWidth;
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auto lutValues = std::vector<int64_t>();
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for (int64_t i = 0; i < lutSize / 2; i++) {
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lutValues.push_back(i);
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}
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for (int64_t i = 0; i < lutSize / 2; i++) {
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lutValues.push_back(0);
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}
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const mlir::Attribute lutAttr = rewriter.getI64TensorAttr(lutValues);
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const mlir::Value lut =
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rewriter.create<arith::ConstantOp>(loc, lutAttr).getResult();
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const mlir::Value max =
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rewriter.create<FHE::ApplyLookupTableEintOp>(loc, outputTy, sub, lut)
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.getResult();
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const mlir::Value add =
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rewriter.create<FHE::AddEintOp>(loc, max, maxEintOp.y()).getResult();
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rewriter.replaceOp(maxEintOp, {add});
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return mlir::success();
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};
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};
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namespace {
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struct FHEMaxTransform : public FHEMaxTransformBase<FHEMaxTransform> {
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void runOnOperation() final;
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};
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void FHEMaxTransform::runOnOperation() {
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auto target = mlir::ConversionTarget(this->getContext());
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target.addLegalDialect<arith::ArithmeticDialect>();
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target.addLegalDialect<FHE::FHEDialect>();
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target.addIllegalOp<FHE::MaxEintOp>();
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auto patterns = mlir::RewritePatternSet(&this->getContext());
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patterns.insert<MaxEintPattern>(&this->getContext());
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mlir::Operation *op = this->getOperation();
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if (mlir::applyPatternsAndFoldGreedily(op, std::move(patterns)).failed()) {
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this->signalPassFailure();
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}
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}
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} // namespace
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namespace mlir {
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namespace concretelang {
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std::unique_ptr<mlir::OperationPass<>> createFHEMaxTransformPass() {
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return std::make_unique<FHEMaxTransform>();
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}
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} // namespace concretelang
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} // namespace mlir
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